u_packet.pas

linux program to read packet data

(*
 * One Way Network Sniffer (OWNS)
 * Copyright (C) 2001-2002 OWNS
 *
 * http://owns.sourceforge.net/
 * http://www.owns.st
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *)

(*
 * $Id: u_Packet.pas,v 1.2 2002/11/23 21:49:50 owns Exp $
 * determines which type of packet is contained in the data
 *)

unit u_Packet;
interface
uses u_EthernetFrame, u_IPPacket, u_TCPPacket;

function getPacket(uBuffer: PChar) : TEthernetFrame;

implementation

// return a TPacketTCP, TPacketIp or TPacketEthernet
function getPacket(uBuffer: PChar) : TEthernetFrame;
var
  pEthernetHdr: PETHERNET_HDR;
  pIPHeader: PIP_RHDR;
  nProto, nIPProto: integer;
begin
  pEthernetHdr := PETHERNET_HDR(uBuffer);
  nProto := TOUSHORT(@(pEthernetHdr^.Protocol[0]));

  case nProto of
  PROTO_IP:
        begin
          pIPHeader := PIP_RHDR(@(pEthernetHdr^.Data[0]));
          nIPProto := pIPHeader^.Protocol;

          case nIPProto of
              //TCP
              6: result := TTCPPacket.Create(uBuffer);
              else
                result := TIPPacket.Create(uBuffer);
              end;
            end;
  else
    result := TEthernetFrame.Create(uBuffer);
  end;
end;

end.